What are a few examples of how Reverend Parris started and perpetuated the Salem Witch Trials in the play, The Crucible?

If you watch Parris in the opening scene, his biggest
concern is his reputation. He is less concerned with Betty's condition than he is about
what his parishoners are going to think. This effort to hide put a series of events into
play that took a dangerously deadly turn. Had Parris been more concerned about Betty's
well-being and promised no retribution to Abigail, she likely would not have begun the
set of lies that began that first scene.

Later, Parris is
concerned with his salary (once again, a selfish purpose). In seeking an answer or an
end to this means, he finds himself at odds with church attender John Proctor. To
further the plot, John's attendance or lack thereof is brought to light by Parris and a
personal bout between the two of them begins. Parris allows himself to be played by
Thomas Putnam who also has angst for Proctor.

As the play
nears the end of the third act, Parris is supporting all accusations of witchcraft that
the girls make and seems to be out for revenge although he likely names it justice or
spiritual morality.

By the end, Parris begins to understand
that way too many people are being condemned and that they are good
people. Unfortunately by that point, it is too late. This demonstrates his understanding
of the perpetuation of the Trials.